Pliers for crimping thimbles on electric cables

ABSTRACT

The object of the invention is a pair of crimping pliers that comprises two arms ( 10 ) and ( 12 ), a fixed jaw and a movable jaw ( 34 ), which is articulated in regard to the two arms, and a hinge link interposed between the two arms.  
     This pair of pliers displays an angular point for forming an arch perpendicular to which is positioned the axis A 3.    
     The present pair of pliers also has angular values and ratios of given lengths.

[0001] The present invention refers to a pair of crimping pliers,particularly for joining terminals to electric cables.

[0002] The ends of electric cables have to include connecting elements,such as different types of terminals, in order to provide connectionsthat depend on the applications.

[0003] Nevertheless, the mode of fixation always remains the same andconsists in a deformation of one part of the terminal, forming a sleevein which a cable is preferably inserted. This deformation action iscalled crimping.

[0004] The dimensions of the terminals vary according to theapplications, but remain of necessity reduced, because the pair ofpliers is operated by hand.

[0005] On the other hand, the applied force required for obtaining agood quality crimping of terminals on the cables remains important andan arrangement of levers is provided for these pliers for multiplyingthe manual force applied by the operator.

[0006] Known from U.S. Pat. No. 2,814,222 is a pair of crimping pliersthat consists of a movable jaw and a multiplying lever.

[0007] This pair of pliers is simple, but the straight upper armsupports all of the stresses generated by the pressure of the movablejaw and the axis of rotation of the movable jaw is subjected to strongstresses. The crimping force is weakly multiplied.

[0008] In general, the tools of most recent prior art, particularlythose described in the patent applications EP A 536,641 and EP A 536,652comprise one arm, the end of which constitutes a fixed jaw, and a secondarm, which operates, through a system of levers, a movable jaw thatrotates around a pivot point that is an integral part of the first arm;when the operator squeezes the arms, this causes the movable jaw to comeagainst the fixed jaw with a considerable squeezing force.

[0009] Any element interposed between the two jaws is subjected to themultiplied squeezing force obtained through the system of levers.

[0010] Moreover, known from U.S. Pat. No. 5,280,716 is a tool of thegeneral type above, the two arms of which are joined to each otherthrough an articulated hinge link on, on the one hand, a fixed axis thatis an integral part of the arm bearing the fixed jaw and, on the otherhand, a movable axis in an oblong opening placed in the other arm.

[0011] In a likewise known manner, the fixed jaw can be advantageouslyfurnished with a turret that bears a number of indentations with a meansof indexing this turret so that the desired indentation is maintainedwith respect to the movable jaw during the squeezing action.

[0012] Provided for in the known arrangements is a strong multiplicationbut a small opening of the jaws, which is not particularly adapted tothe operator, especially when, prior to crimping, the terminals displaya considerable diameter. On the other hand, it is appropriate to reducethe opening of the arms in order to make the manipulations morepractical.

[0013] Moreover, it is necessary to avoid having the stresses at thelevel of the pivot point greater than the forces transmitted at thelevel of the jaws themselves, because, in this case, the efficiency isnot optimal.

[0014] These pliers are made of light metallic materials, such asaluminum alloys, so as to attain a compromise between the differentfactors such as cost/quality/performance.

[0015] In order to improve these factors still further, it has beenprovided that such pliers be made of composite materials, such asfiber-loaded or fiber-reinforced polymer compositions.

[0016] Nevertheless, particularly in the case of a composite materialrealization, it is necessary to pursue several objectives and, with thisaim in view, the present invention proposes a pair of crimping pliersthat makes it possible, in particular:

[0017] to reduce the stresses perpendicular to all pivot points to avalue that is less than that of the force exerted at the level of thejaws;

[0018] to produce a significant opening of the jaws for a givenmultiplied force, but a limited opening of the arms; and

[0019] to retain a significant multiplied force so as to ensure a goodquality of crimping.

[0020] To this end, the object of the present invention is a pair ofcrimping pliers, particularly for terminals on electric cables,comprising an upper arm bearing a fixed jaw with at least oneindentation at its end, a lower arm, a hinge link that is interposedbetween said upper arm and said lower arm and that is articulated aroundthe axes A1, A2, a movable jaw that has an indentation and isarticulated, in relation to the upper arm, around an axis A3 and, inrelation to the lower arm, around an axis A4, characterized in that thedistance between the axes A1 and A2 is roughly equal to the distancebetween the axes A3 and A4 and in that the upper arm displays an angularpoint defining a body of the upper arm and a head of the upper arm, withthe internal angle a, directed towards the lower arm, being less than180°.

[0021] In accordance with another characteristic feature, thedisplacement circle of the axis A2 in relation to the axis A1, thedisplacement circle of the axis A4 in relation to the axis A2, and thedisplacement circle of the axis A4 in relation to the axis A3 have aroughly identical diameter.

[0022] Such a pair of pliers is particularly noteworthy in that theparticular arrangement of the axes of articulation makes it possiblelargely to equilibrate the stresses at the level of the different axes,while producing a significant force at the level of the jaws and, at thesame time, having a limited opening of the jaws.

[0023] In accordance with a characteristic arrangement, the angle α is120°.

[0024] In accordance with another characteristic feature, the axis ofarticulation, A3, of the movable jaw is positioned perpendicular to theangular point.

[0025] Moreover, the axis A1 is positioned behind the axis A2 inrelation to the jaws.

[0026] The pair of pliers is also characterized in that different angleshave defined values:

[0027] the angle β, defined by the segments [A4-A3] and [A4-M2], is lessthan 90°;

[0028] the angle ε, defined by the segments [A1-A3] and [A1-A2], is lessthan 90°; and

[0029] the opening angle γ of the upper arm (10) and lower arm (12) isless than 50°.

[0030] According to a refined variant, the fixed jaw comprises a turret,provided with indentations and mounted so as to rotate around an axis,and provided with a means of indexing the position of this turret.

[0031] The present invention is now described in detail in regard to apreferred, non-limiting embodiment that is illustrated in the appendeddrawings, among which the different figures represent the following:

[0032]FIG. 1, a perspective view of a pair of crimping pliers inaccordance with the present invention, in closed position;

[0033]FIG. 2, a side view from above of this same pair of pliers;

[0034]FIG. 3, a simplified and side view from above of the pair ofpliers in accordance with the present invention, in open position;

[0035]FIG. 4, a simplified and side view from above of the pair ofpliers in accordance with the present invention, in closed position;

[0036]FIGS. 5A and 5B, views of the same pair of pliers in open andclosed positions, showing the displacements following the circles of theprinciple points of articulation.

[0037] The pair of pliers in accordance with the present invention,represented in FIG. 1, comprises an upper arm 10 and a lower arm 12.Each arm is composed of two plates or is cast so as to leave a centralgap 14 and 16 that permits the displacements of the different pieces.

[0038] The upper arm bears a safety catch 18 that engages between thetwo arms. In every case, this catch prevents contact of the armsperpendicular to the hand grip zone. Indeed, in the event that a piecebreaks or there is a handling error, it serves to prevent any accidentalpinching of the fingers of the operator.

[0039] In the case of a metallic realization, the plates are riveted andthe rivets 20 appear in the figures.

[0040] A hinge link 22 is interposed between the arms 10 and 12. Thishinge link is mounted in an articulated manner around the axis A1 inrelation to the upper arm 10 and around the axis A2 in relation to thelower arm 12. The axis A1 is situated behind the axis A2 in relation tothe jaws.

[0041] The upper arm 10 bears a fixed jaw 24 at its end with anindentation M1. This arm displays, in addition, an angular point 26 thatdefines a body 10-1 of the upper arm and a head 10-2 of the upper arm.

[0042] The internal angle α, directed towards the lower arm and definedby the body 10-1 and the head 10-2 of the upper arm, is less than 180°,preferably of the order of 120°.

[0043] In the preferred embodiment represented, the head 10-2 of theupper arm is equipped with a turret 28 that is mounted so as to rotatearound an axis 30. This turret comprises several indentations 32 on itsperiphery and a means of indexing, which is not represented and makes itpossible to maintain one, M1, of these indentations 32 in fixedposition.

[0044] This is only a refinement of the pair of pliers in accordancewith the invention; the upper arm 10 could bear, at its end, a singleindentation that is fixed and of given profile, without changing theconstitutive elements of the pair of pliers, providing a solution of theposed problems in the same way and affording the same advantages.

[0045] A movable jaw 34 is interposed between the upper and lower arms.This jaw is articulated around an axis A3 in relation to the upper arm10 and around an axis A4 in relation to the lower arm 12. This jaw bearsan indentation M2 at its end, which is intended to engage theindentation M1 when the pair of pliers is closed, as well be explainedlater.

[0046] The angle β, defined by the segment [A4-A3] and [A4-M2], also hasa given value, which is less than 90° C. As for the distances d[A1,A2]and d[A3,A4], they are roughly equal.

[0047] It can be seen in the arrangement presented that the axis ofarticulation, A1, is in back on the upper arm so as to increase thedistance d[A1,A3]. Moreover, this makes it possible to extend thedistance d[A1,A2] so as to make it roughly identical to the distanced[A3,A4], as was pointed out above. Thus, d[A1,A2]/d[A3,A4] is close to1.

[0048] A third angle, the opening angle γ, has to be kept at a maximumvalue, preferably a value less than 50°.

[0049] From FIGS. 5A and 5B, it is possible to compare the displacementcircles of the different axes.

[0050] It is seen that the principle axes of the pair of pliers inaccordance with the present invention move in relation to one another byfollowing circles of roughly identical diameter. This translates into anequilibrated distribution of the stresses on each of the axes, becausethe arms of the lever required for the multiplication are of the sameorder of length.

[0051] The circle C2-1 corresponds to the displacement of the axis A2 inrelation to the axis A1.

[0052] The circle C4-2 corresponds to the displacement of the axis A4 inrelation to the axis A2.

[0053] The circle C4-3 corresponds to the displacement of the axis A4 inrelation to the axis A3.

[0054] It is also seen that moving the axis A1 toward the back, inrelation to the arrangements of prior art, makes it also possible tolengthen the distance covered by the arc of the circle described by theaxes A2 and A4 in relation to the axis A1 and A3.

[0055] The force exerted by the movable jaw on the fixed jaw is directedfrom M2 toward M1 or toward the axis 30 of the turret when one isprovided for.

[0056] The axis A2 is positioned at the vertex of an arch of stressrecovery defined by the two segments [A1-A3] and [A3-(30)] or [A3-M1],depending on the arrangement. This reinforces the strength at thispoint.

[0057] During all the movement of opening and especially of closing thepair of pliers, the angle δ stays at values less than 90°.

[0058] The pair of pliers realized in this way offers a certainergonomics, which is due largely to the reduced degree of opening of thearms as well as to the equilibrated stresses on the different axes,which thereby increases the longevity of this pair of pliers.

[0059] Such a pair of pliers can be made of composite materials withoutfearing points of fragility produced by very significant localizedstresses.

1. A pair of crimping pliers, particularly for terminals on electriccables, comprising an upper arm (10) bearing a fixed jaw with at leastone indentation (M1) at its end, a lower arm (12), a hinge link (22)that is interposed between said upper arm and said lower arm and that isarticulated around the axes (A1,A2), a movable jaw (34) that has anindentation (M2) and is articulated, in relation to the upper arm,around an axis (A3) and, in relation to the lower arm, around an axis(A4), characterized in that the distance between the axes A1 and A2 isroughly equal to the distance between the axis A3 and A4 and in that theupper arm displays an angular point (26) defining a body (10-1) of theupper arm and a head (10-2) of the upper arm, with the internal angle α,directed towards the lower arm, being less than 180°.
 2. The pair ofcrimping pliers in accordance with claim 1, further characterized inthat the angle α is 120°.
 3. The pair of crimping pliers in accordancewith claim 1 or 2, further characterized in that the axis ofarticulation, A3, of the movable jaw (34) is positioned perpendicular tothe angular point (26).
 4. The pair of crimping pliers in accordancewith any of the preceding claims, further characterized in that the axisA1 is positioned behind the axis A2 in relation to the jaws.
 5. The pairof crimping pliers in accordance with any of the preceding claims,further characterized in that the displacement circle (C2-1) of the axisA2 in relation to the axis A1, the displacement circle (C4-2) of theaxis A4 in relation to the axis A2, and the displacement circle (C4-3)of the axis A4 in relation to the axis A3 have a roughly identicaldiameter.
 6. The pair of crimping pliers in accordance with any of thepreceding claims, further characterized in that the angle β, defined bythe segments [A4-A3] and [A2-M2], is less than 90°.
 7. The pair ofcrimping pliers in accordance with any of the preceding claims, furthercharacterized in that the angle δ, defined by the segments [A1-A3] and[A1-A2], is less than 90°.
 8. The pair of crimping pliers in accordancewith any of the preceding claims, further characterized in that theopening angle γ, defined by the upper (10) and lower (12) arms, is lessthan 50°.
 9. The pair of crimping pliers in accordance with any of thepreceding claims, further characterized in that the fixed jaw (24)comprises a turret (28), provided with indentations (32) and mounted soas to rotate around an axis (30), and provided with a means of indexingthe position of the turret.
 10. The pair of crimping pliers inaccordance with any of the preceding claims, characterized in that it ismade of composite materials.